1. Field of the Invention
The invention generally relates to an optical module and a display apparatus, and more particularly to a lens array module and a projection apparatus.
2. Description of Related Art
The projection apparatus has not been replaceable in the display field due to the small footprint device being capable of generating a large image. Moreover, the size of the large image can be much larger than the size of a typical flat panel display. This type of large image is especially suitable for reports, conferences, or the playback of movies.
In order for the light emitted by the light source in the projection apparatus to be efficiently transmitted to the light valve, conventional projection apparatuses adopt two lens arrays. Moreover, each of the lenses in a first lens array directly faces a lens in a second lens array. However, for the part of the illumination beam emitted by the light source that is obliquely incident onto a lens of the first lens array at a large angle, typically this part of the beam cannot enter the corresponding lens of the second lens array. Rather, this part of the illumination beam enters another lens beside the corresponding lens, causing a stray light to be transmitted to two long sides at the top and bottom of the rectangular light valve, and thereby contributing to an energy loss in a phenomenon referred to as crosstalk. From another perspective, a part of the light emitted from a lens of the first lens array is transmitted to a region outside of the area encompassed by the corresponding lens in the second lens array. Therefore, a stray light is transmitted to two sides of the light valve and cannot be effectively transmitted to the light valve.
Hence, even though the two lens arrays in the conventional projection apparatuses are for enhancing light utilization efficiency, the degree of light utilization efficiency enhancement is still limited due to the aforementioned reasons.
U.S. Pat. No. 6,860,607 discloses a lens array, in which a small lens on one of two rows at the centermost area of a second lens array surface is the thickest. Moreover, U.S. Pat. No. 5,418,583 discloses a lens array, in which the size of a small lens on a second lens array surface is adjusted according to the size and shape of the light spot generated by a light beam emitted by a first lens surface.